Answer: 0.814 M MgS
Step-by-step explanation:
I am assuming that 34.1 is in Grams if not this answer is propably not correct.
34.1 g MgS / 56.369 MgS(molar mass from Periodic table) = 0.605 moles
Molarity - moles / Liter
M= 0.605 / 0.743 Liter =0.814 M